Gas supply apparatus for fluid tanks



May 14, 1940- H. WEICHSEL GAS SUPPLY APPARATUS FCR FLUID TANKS Filed May 22; 1937 2 Sheets-Sheet 1 INVENTOR. HANS WEICHSEL BY 52 ATTORNEY.

May 14, 1940,

H. WEICHSELV 2,200,610 GAS SUPPLY APPARATUS FOR FLUID TANKS Filed May 22', 1951 2 Sheets-Sheet 2 FIG.2.

FIG.3.

INVENTOR. HA HS WEICH SEL ATTORNEY.

Patented May 14, 1940 UNETE STATESl RATENT OFFKCE GAS SUPPLY APPARATUS FOR FLUID TAN [implication May 22, 1937, Serial No. 144,321

5 Claims,

My invention relates to apparatus for supplying inert to a space above the fluid level in oil-filled transformer tanks and other liquid containing tanks in which it is desirable that the 5 space above the liquid be filled with inert gas (such. as nitrogen or carbon dioxide, for example) rather than with air.

The general object of my invention is to provide improved for the above purpose which. will operate automatically and which will reduce the waste of inert gas to a minimum and under some conditions of operation of the transformer and other apparatus will avoid all loss of gas it valves and. joints are kept gas-tight.

My invention comprises a gasoinetcr of novel construction by means of which inert gas will be maintained under constant pressure through out a considerable range of variation of volume of the. gas space to be occupied by it in. the fluid containing tank.

In the accompanying drawings Figure l illustrates a form of apparatus embodying my invention and shown association with an oil-fil1ed transformer; Figure 2 is a circuit diagram illustrating the controlling circuits for the motor which operates the gasometer supply valve; and Figure a diagram showing gas pressure in relation. to the position of the weight element of the gasometer.

Referring to Figure l, the electrical. transformer l is shown in an oil containing tank 2 provided with a sealed cover the oil level indicated being that assumed to exist during operating conditions of the transformer in which the oil temperature is less than the maximum th may exist under other operating conditions. The gasoineter comprises a cylindrical lower casing part l and upper casing part 5 and between these parts is clamped the periphery of a flexible M bag or balloon element 5, which ele ,..ent forms with casing part t a variable volume of inert containing space connected to the upper part of the transformer tank by means of pipe 8.

bag element should be formed of material not re- 45 active to the gas supplied to the transformer nor to such gases be evolved from the transformer oil. Synthetic rubber mate ials such those on the market under the trade names duprene and thiokol are suitable for this purpose. The flexible bag carries a weight element I on its upper surf ace which, as shown, is provided with a thin walled cylindrical extension la the function of which is to provide bearing for part of the surface of the torus portion 26 of the bag during the rise and fall of the central (Cl. seees) portion of the bag in operation of the apparatus. The wall of portion la is made thin in comparison with the bottom portion of the weight in order to maintain the center of gravity of the weight as low as possible. The dotted lines in the figure show the position of the weight and under condition of such increase in gas containing space in the transformertank that slight further increase would require the admission of additional gas into the gasometer.

The numeral il indicates a supply tank of inert in which the gas under relatively high pressure and from which it may be delivered through pipe ill to the gasoineter. This delivery is con trolled by suitable pressure reducing valve I! and a gas shut-oil valve l2. his shut-oil valve is opened and closed b means of a reversible elec tric motor E3 controlled by the switch contacts Hi and at the bottom of the gasometer, and contacts Hl-ll and l3-i9 in the top element 5 of the gasometer casing. The control circuits are indicated in Figure 3 wherein is shown solenoid operated 'motor switch 2t and a battery 2! for supplying motor operating current. In practice current would ordinarily be supplied by a small transformer.

Referring now to the operation of the appara-- tus just described, a reduction in temperature of the oil in the transformer will increase the gas containing space in the transformer with the result that the weight member ii will descend and reduce the gcsoineter volume to the extent necessary to transfer additional gas to the transformer tank and the pressure of the gas will remain the same since such pressure depends upon weight '7. If at the time of occurrence of the temperature reduction. above assumed, the. bag and weight occupy the position shown in dotted lines of the figure, the descent of these parts will close contacts i l-l 5 whereby the battery current will flow through the solenoid to bring; the motor control switch 2@ to a position causing the motor to operate in a direction to open valve 12 to permit additional gas to flow into the gasometer through pipe ill. This flow will continue until the bag and weight are lifted to a position where contacts lll ll and ISM- it are closed, at which time solenoid will bring the motor switch 2% to a position to cause the motor to operate in the opposite direction. and close the valve it. While with the circuits shown the rotor is always energized and, therefore, should be of the stalled type, known means for opening the circuit of a valve actuating motor when closed or open position of the valve is reached, can be employed.

Should the temperature of the oil in the trans former increase at the time the weight is at its uppermost position in the gasometer, the increased pressure resulting from the rise of the oil level will open the safety valve 24 at the top of the transformer tank to permit reduction of gas pressure to the value determined by the pressure setting of that valve. It is not necessary that the normal pressure on the inert gas be more than slightly above atmospheric pressure and the weight element may be made only sufficiently heavy to increase the inert gas pressure about three or four ounces per square inch above the atmospheric pressure (effective on the outside of the bag by reason of the breather tube 27 in the top of the gasometer casing).

In the initial installation of the apparatus, the air may be eliminated from, the transformer by opening purge valve 255 in the lid of the transformer and supplying inert gas through pipe 8 until all the air has been exhausted. Preferably, this initial filling should be under the lowest tem perature conditions to which the transformer is subject whereby, unless there is loss of gas due to gas leaks, the apparatus will never require additional gas from the tank if the gasometer is large enough that at maximum opera-ting temperature the gasometer weight does not rise to the limit of its upward movement and, therefore, no condition occurs resulting in escape of gas through safety valve 24. However, under my invention it is permissible to make the gasometer smaller than is necessary to achieve the above end and with the only disadvantage that after the occurrence of a condition that results in the escape of gas through the safety valve, lower temperature condition might be reached which. would result in more gas being admitted to the gasonieter. Thus it is possible to compare the cost of gas lost with the factors of original cost of the gasometer and the space available for it, in determining the size of the gasometer to be installed in association with a particular transformer. Ordinarily it would be feasible and desirable to so proportion the gasometer for the load cycle of the transformer and the temperature ranges of the surrounding atmosphere that little or no inert gas will be valved to the atmosphere. Therefore, my invention results in sub stantial advantage in operating cost over any apparatus for a similar purpose known to me.

The clearance between the wall la of the weight element and the wall of the gasometer should be relatively small because. the smaller this clearance the less the strain on the bag material, such strain being proportional to the area of the surface of the bag which is not in contact with either the weight member or the wall of the gasometer. Another reason for employing a small clearance is that the smaller this clearance the less wrinkling occurs in the bag material as the center of the bag rises and falls. The clearance of about one inch at the point referred to, has been found satisfactory for gasometers of diameter of from 4-0 to 60 inches.

In order to hold the center of gravity of the weight as low as possible, it is advisable, in addi tion to making the wall la thin, that its height be less than that of the bag in full inflated condition, but the height should be sufficiently great that the surface area of the portion of the bag that contacts with neither the weight element nor the wall of the casing at the lowest position of the weight (see dotted lines in the figure) is not sufficiently great to result in undue strain on the bag material.

Referring to the curve shown in Figure 3, this illustrates the relation between the gas pressure and the position of the gasometer weight (extent of bag inflation). The apparatus should be so proportioned that the valve 25 will be opened at the point on the curve indicated by dotted line b. Under such condition, of course, the valve will close before the pressure has risen substantially above this point. How high the pressure may use after closing of the gas supply valve, is determined, as heretofore indicated, by the setting of safety valve 24 on the transformer tank.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. The combination of a sealed gas container having a variable volume gas space, variable volume means connected thereto to maintain constant gas pressure in said space over a predetermined range, said last named means comprising a container having a weighted flexible wall, and means controlled by the position of said wall for automatically supplying a predetermined volume of additional gas to said container, said means comprising an electrically-operated valve and two control circuits therefor, one of said circuits being controlled by a switch actuated when the flexible wall approaches the upper limit of its travel and the other circuit by a switch actuated when the flexible wall approaches the lower limit of its travel.

2. The combination of a sealed gas container having a variable volume gas space, means forming a variable volume gas chamber connected thereto for supplying gas to said space and receiving gas therefrom said chamber having a weighted flexible wall, a source of inert gas under high pressure connected to said gas chamber, a gas shut-off valve in said connection, a pressure reducing valve between the gas shut-off valve and said high pressure gas container, and means for opening and closing said shut-off valve, said means being responsive to predetermined changes in volume of the gas chamber,

3. A gasometer apparatus for the purpose described comprising a gas-tight container having a portion of its wall formed of flexible material,

and a weight element supported by said wall and provided with an upward cylindrical extension forming a bearing surface for portions of the flexible material, the weight of said extension being small in proportion to that of the portion of the weight element engaging the upper surface of the flexible wall.

4. A gasometer apparatus for the purpose described comprising a gas-tight container having a portion of its wall formed of flexible material, a weight element supported by said wall and provided with an upward cylindrical extension forming a bearing surface for portions of the flexible material, the weight of said extension being small in proportion to that of the portion of the weight element engaging the upper surface of the flexible wall, and a casing element embracing said weight element and forming therewith an annular space for receiving the exterior portions of the flexible material during rise and fall of the weight.

5. A gasometer apparatus for the purpose described comprising a gas-tight container having a portion. of its wall formed of flexible material, a weight clement supported by said wall and provided with a cylindrical extension, and a casing element embracing said weight element and ex- Ill tension in the positions of the latter under which the container capacity is either at maximum or more than half maximum and. forming with the extension a narrow annular space for receiving portions of the flexible wall, said casing, weight extension, and flexible wall being so related that under said last mentioned conditions as tocontainer capacity all of the flexible Wall other than the torus portion bears either on the casing or on the weight element.

HANS WEICHSEL. 

